This invention relates generally to epoxide compounds and more particularly to the curing of such compounds.
Epoxide compounds have been found to be useful for encapsulating or potting electronic circuitry. This involves pouring the liquid components over the circuitry and then curing or polymerizing the liquid to a solid polymer.
In the prior art process, the electronic circuitry is typically heated to about 65.degree. C. (150.degree. F.) while evacuated for an extended time such as overnight to avoid any subsequent voids in the encapsulant. The liquid resin is then also heated to the same temperature and evacuated for 10-15 minutes after which it is poured into the mold containing the circuitry. (There are commercially available devices having separate chambers which can be independently evacuated and heated with a provision for pouring when desired from the upper chamber.) The mold is then removed and placed in an oven where it is gradually heated to 104.degree. C. (220.degree. F.). After 16 hours, the mold is removed and cooled to room temperature. The potted circuitry is then ready for use.
The foregoing prior art process, while achieving a useful potting compound, involves temperature changes which may result in harmful residual stresses because of the different coefficients of thermal expansion of the electronic circuitry and the resin.